The present invention relates to a spring clamping construction for securing a punch on the ram of a press and a hydraulic motor construction which selectively counteracts the spring force to permit the rapid removal and installation of punches.
By way of background, the normal way of holding an elongated punch on the ram of a press is by a plurality of screws which are spaced lengthwise of an elongated movable jaw, each of which must be loosened and tightened manually to move the movable jaw toward and away from a fixed jaw which cooperates with the movable jaw to hold a punch therebetween. The manual tightening and loosening of the screws is time-consuming, and when it is considered that punches may require changing many times a day, the foregoing structure causes the press to be out of operation for relatively long periods, thereby reducing its productivity. In other types of prior art presses, the movable jaw is held in locking engagement relative to the fixed jaw by hydraulic pressure which must be exerted on the movable jaw at all times to maintain the locking engagement. It is with obviating the foregoing deficiencies of prior punch clamping structure of presses that the present invention is concerned.